Bleeding Kansas is the name given to a small scale civil war that took place in Kansas territory 1855-57 over the issue of slavery. It followed the Kansas-Nebraska Act, which introduced the idea of popular sovereignty. The voters got to decide on whether Kansas would have slavery, so pro and anti-slavery forces in other states subsidized armed immigrants, who fought it out. Major violence took place when pro-southern elements from Missouri burned Lawrence in retaliation by the killings of pro-slavery men by John Brown. President James Buchanan intervened on the pro-slavery side, but that broke apart the Democratic Party, as Stephen Douglas was outraged by Buchanan's violation of democracy.